Fcγ RIIb protects from reperfusion injury by controlling antibody and type I IFN-mediated tissue injury and death.

Intestinal ischemia and reperfusion (I/R) is accompanied by an exacerbated inflammatory response characterized by deposition of IgG, release of inflammatory mediators, and intense neutrophil influx in the small intestine, resulting in severe tissue injury and death. We hypothesized that Fcγ RIIb activation by deposited IgG could inhibit tissue damage during I/R. Our results showed that I/R induction led to the deposition of IgG in intestinal tissue during the reperfusion phase. Death upon I/R occurred earlier and was more frequent in Fcγ RIIb-/- than WT mice. The higher lethality rate was associated with greater tissue injury and bacterial translocation to other organs. Fcγ RIIb-/- mice presented changes in the amount and repertoire of circulating IgG, leading to increased IgG deposition in intestinal tissue upon reperfusion in these mice. Depletion of intestinal microbiota prevented antibody deposition and tissue damage in Fcγ RIIb-/- mice submitted to I/R. We also observed increased production of ROS on neutrophils harvested from the intestines of Fcγ RIIb-/- mice submitted to I/R. In contrast, Fcγ RIII-/- mice presented reduced tissue damage and neutrophil influx after reperfusion injury, a phenotype reversed by Fcγ RIIb blockade. In addition, we observed reduced IFN-ß expression in the intestines of Fcγ RIII-/- mice after I/R, a phenotype that was also reverted by blocking Fcγ RIIb. IFNAR-/- mice submitted to I/R presented reduced lethality and TNF release. Altogether our results demonstrate that antibody deposition triggers Fcγ RIIb to control IFN-ß and IFNAR activation and subsequent TNF release, tailoring tissue damage, and death induced by reperfusion injury.

N-acetylcysteine reduces amphotericin B deoxycholate nephrotoxicity and improves the outcome of murine cryptococcosis.

Cryptococcosis is a life-threatening fungal infection, and its current treatment is toxic and subject to resistance. Drug repurposing represents an interesting approach to find drugs to reduce the toxicity of antifungals. In this study, we evaluated the combination of N-acetylcysteine (NAC) with amphotericin B (AMB) for the treatment of cryptococcosis. We examined the effects of NAC on fungal morphophysiology and on the macrophage fungicidal activity 3 and 24 hours post inoculation. The therapeutic effects of NAC combination with AMB were investigated in a murine model with daily treatments regimens. NAC alone reduced the oxidative burst generated by AMB in yeast cells, but did not inhibit fungal growth. The combination NAC + AMB decreased capsule size, zeta potential, superoxide dismutase activity and lipid peroxidation. In macrophage assays, NAC + AMB did not influence the phagocytosis, but induced fungal killing with different levels of oxidative bursts when compared to AMB alone: there was an increased reactive oxygen species (ROS) after 3 hours and reduced levels after 24 hours. By contrast, ROS remained elevated when AMB was tested alone, demonstrating that NAC reduced AMB oxidative effects without influencing its antifungal activity. Uninfected mice treated with NAC + AMB had lower concentrations of serum creatinine and glutamate-pyruvate transaminase in comparison to AMB. The combination of NAC + AMB was far better than AMB alone in increasing survival and reducing morbidity in murine-induced cryptococcosis, leading to reduced fungal burden in lungs and brain and also lower concentrations of pro-inflammatory cytokines in the lungs. In conclusion, NAC + AMB may represent an alternative adjuvant for the treatment of cryptococcosis.

The Th2 Response and Alternative Activation of Macrophages Triggered by Strongyloides venezuelensis Is Linked to Increased Morbidity and Mortality Due to Cryptococcosis in Mice.

Cryptococcosis is a systemic mycosis that causes pneumonia and meningoencephalitis. Strongyloidiasis is a chronic gastrointestinal infection caused by parasites of the genus Strongyloides. Cryptococcosis and strongyloidiasis affect the lungs and are more prevalent in the same world regions, i.e., Africa and tropical countries such as Brazil. It is undeniable that those coincidences may lead to the occurrence of coinfections. However, there are no studies focused on the interaction between Cryptococcus spp. and Strongyloides spp. In this work, we aimed to investigate the interaction between Strongyloides venezuelensis (Sv) and Cryptococcus gattii (Cg) in a murine coinfection model. Murine macrophage exposure to Sv antigens reduced their ability to engulf Cg and produce reactive oxygen species, increasing the ability of fungal growth intracellularly. We then infected mice with both pathogens. Sv infection skewed the host's response to fungal infection, increasing lethality in a murine coinfection model. In addition to increased NO levels and arginase activity, coinfected mice presented a classic Th2 anti-Sv response: eosinophilia, higher levels of alternate activated macrophages (M2), increased concentrations of CCL24 and IL-4, and lower levels of IL-1ß. This milieu favored fungal growth in the lungs with prominent translocation to the brain, increasing the host's tissue damage. In conclusion, our data shows that primary Sv infection promotes Th2 bias of the pulmonary response to Cg-infection and worsens its pathological outcomes.

Investigating potential associations between neurocognition/social cognition and oxidative stress in schizophrenia.

INTRODUCTION: Deficits in neurocognition and social cognition play a critical role in the functional impairment of patients with schizophrenia. Increased oxidative stress has been evidenced in schizophrenia. Increased oxidative stress can affect neuronal function and lead to impairments in neurocognitive functions (especially working memory) and social cognition. OBJECTIVE: To investigate deficits in neurocognition and social cognition and their potential association with oxidative stress biomarkers in schizophrenia. MATERIAL AND METHODS: Eight-five clinically stable patients with schizophrenia and 75 controls were enrolled in this study. Neurocognition was evaluated through the Brief Assessment of Cognition in Schizophrenia (BACS). Social cognition was assessed through the Hinting Task - a test of theory of mind - and an emotion processing test, Facial Emotion Recognition Test (FERT-100). Oxidative stress was assessed by measuring serum levels of glutathione (GSH) and thiobarbituric acid reactive substances (TBARS). RESULTS: Patients had decreased serum levels of GSH (Z=3.56; p<0.001) and increased TBARS (Z=5.51; P<0.001) when compared with controls. TBARS levels are higher in patients using first generation antipsychotics. Higher serum levels of TBARS in patients were associated with poor performance in working memory test (r=-0.39; p=0.002), even when controlling for age and negative symptoms (Standard Beta: -0.36; CI= -2.52 a -13.71). DISCUSSION: The association between greater lipid peroxidation, as assessed by TBARS, and worse performance in working memory corroborates theoretical models of greater vulnerability of schizophrenia to oxidative stress.

Pioglitazone as an adjuvant of amphotericin B for the treatment of cryptococcosis.

Approximately 180,000 people worldwide die from cryptococcosis each year, probably due to the ineffectiveness and toxicity of drugs currently available to treat the disease. Amphotericin B (AMB) is effective for killing the fungus, but has serious adverse effects linked to excessive production of reactive oxygen species which compromise renal function. Pioglitazone (PIO) is a peroxisome proliferator-activated receptor-γ agonist widely repositioned as an adjuvant of various drugs that have toxic effects due to its antioxidant and anti-inflammatory effects. This study evaluated PIO in combination with AMB for the treatment of cryptococcosis. PIO was found to reduce serum creatinine and glutamic-oxalacetic transaminase levels in mice treated with PIO+AMB. In vitro, PIO was able to control harmful oxidative bursts induced by AMB without compromising the antifungal effect. In vivo, PIO+AMB increased the survival rate compared with AMB alone, and improved the morbidity of the animals. PIO+AMB was more efficient than AMB alone for inhibiting fungal transmigration from the lungs to the brain, and killing yeasts that reached the central nervous system, avoiding the establishment of meningoencephalitis. In a phagocytosis assay, PIO did not influence the engulfment and fungicidal activity of macrophages induced by AMB, but reduced the oxidative bursts after the reduction of fungal burden, pointing to control of the pathogen without leading to excessive stress which can be damaging to the host. In conclusion, PIO+AMB was found to ameliorate cryptococcosis in a murine model, indicating that it is a promising therapeutic adjuvant for combating and controlling this fungal infection.